In present-day gas turbines which operate at very high gas temperatures and in order to provide as high an efficiency as possible, a rotor body of a turbine carrying the rotation blading typically must be shielded with respect to the gases of combustion.
In the known prior art, it had been customary to provide a drum rotor which was completely satisfactory at lower heat and stability stresses. At the present time, however, rotors which are composed of individual rotor disks that are welded together in circumferential directions are used in gas turbine plants. In the turbine plants of today, the rotors are subject to higher stresses, essentially both thermal and mechanical.
In disks which are welded together at an outside diameter, a gap between two neighboring rotor blade rows is protected by separate heat localization segments which shield the entire circumference of the gaps. These heat localization segments customarily consist of the same highly heat-resistant material as the blades and like the blades are mounted in circumferential slots of the rotor by fir cone roots. The heat localization segments of this type necessitate a high production requirement and correspondingly high costs.
In gas turbines working at relatively higher circumferential velocities, the disks are, for reasons of stability, welded together along ring-shaped projections. The diameter of the ring-shaped projections is less than the outside diameter of the disks. The radius of the ring-shaped projections is selected such that a diameter change of the ring owing to the centrifugal force is equal to a change in diameter of the rotor disks at the welding point. In this way, the rotor disks are not additionally loaded by reason of the centrifugal force of the rings.
Indeed, with such a rotor arrangement, guide wheel bases are specified in the circular spaces outwardly from these ring-shaped projections in order to separate two neighboring guide wheel stages from each other. In the event of a too large play of the guide wheel base with respect to the rotor, the guide wheel base is streamed with hot gas whereby the guide wheel base and shaft can be overheated. In the event of a guide blade fracture caused thereby, considerable damage to the expensive rotor body in certain circumstances must be anticipated.
The disadvantages of the known prior art are to be avoided with a turbine blade arrangement according to the present invention.
In a turbine blade according to the present invention, the turbine blade is provided with heat localization segments. The turbine blade is especially intended for a gas turbine and further comprises a plurality of covering elements. The covering elements may be formed of one piece with the turbine blade and impede access of a hot working medium to the turbine rotor.